UBS reportedly plans to announce up to 10,000 job cuts worldwide as it slims its investment banking activities.
The cuts are equivalent to up to 16% of its 63,000 workforce.
The Swiss bank's large debt trading business is to be split into a separate unit that will be wound down over time.
UBS declined to comment on the reports.
The bank had total losses of $US42 billion during the 2007-09 financial crisis, particularly due to investments in US sub prime debt, and had to be bailed out by Switzerland.